The present invention relates to an eyeglass lens processing apparatus for processing a peripheral edge of an eyeglass lens.
In an eyeglass lens processing apparatus, when performing processing, such as beveling a peripheral edge of an eyeglass lens, chamfering the edge of the lens, edge positions of a front surface and a rear surface of the lens according to a radius vector of a target lens shape should be known prior to the processing. Therefore, in this kind of the apparatus is provided with a measuring mechanism that includes a feeler for abutting against the front and rear surfaces of the lens and measures an edge position (lens refractive surface shape) of the lens by relatively moving the feeler with respect to lens chuck shafts based on the target lens shape while rotating the lens held by the lens chuck shafts at a constant speed (See, for example, U.S. Pat. No. 4,596,091 (JP-A-H07-148650), U.S. Pat. No. 6,409,574 (JP-A-2000-317796)).
For the eyeglass lens processing apparatus, there is a demand of reducing processing time as much as possible.
Processing time (edge position measurement time) of the lens can be shortened by increasing a rotation speed of the lens. Incidentally, the feeler is abutted against the refractive surface of the lens with a light pressure. When the target lens shape whose radius vector is abruptly changed is measured, if the rotation speed of the lens is increased, a moving position in an abutting direction in which the feeler is abutted against the refractive surface of the lens (axis direction of the lens chuck shafts) is also abruptly changed. At this time, due to influence of movement of the feeler, such as inertia, gravity, and the like, the feeler cannot follow the refractive surface of the lens or the feeler deviates from the radius vector path of the target lens shape, thereby deteriorating measuring accuracy.